Varun Narayanan
February 17, 2026
What is SSH ?
A simple explanation of what SSH is and how it works
What is SSH ?
SSH, or Secure Shell, is a cryptographic network protocol used for secure remote login and other secure network services over an insecure network. It provides a secure way to access and manage remote systems, such as servers, without exposing sensitive information like passwords or data to potential eavesdroppers.
How SSH Works
SSH works by establishing a secure connection between a client (your computer) and a server (the remote system you want to access). This connection is encrypted, meaning that any data transmitted between the client and server is scrambled and unreadable to anyone who might intercept it. This encryption is achieved through a combination of public-key cryptography and symmetric-key cryptography.
Core SSH Protocol Versions
- SSH-1 (1995) - The original version, now considered obsolete and insecure due to vulnerabilities
- SSH-2 (2006) - Current standard defined by IETF, featuring enhanced security, improved encryption, and better authentication
Use Cases
- Remote Server Management
- Software Development
- Network Administration
- Secure File Transfer
- Remote Access to Databases
SSH Connection Types
| Type | Description | Use Case |
|---|---|---|
| Interactive SSH | Standard shell access for remote login | System administration, remote server management |
| Non-interactive SSH | Automated command execution without shell | Scripts, CI/CD pipelines, automation |
| SSH Tunneling (Port Forwarding) | Encrypted tunnels for other protocols | Secure database access, bypassing firewalls |
| SFTP/SCP | Secure file transfer protocols | Uploading/downloading files securely |
| SSH Agent Forwarding | Authentication credential forwarding | Accessing multiple servers without re-authenticating |
| SSH Jump Host / Bastion | Proxy connections through intermediate hosts | Accessing private networks securely |